| This article is excerpted from the current feature in Environmental Building News Copyright 2003. |
Those of us who drive diesel vehicles or heat our homes or businesses with heating oil enjoy the savings this fuel provides – I’ve driven over 800 miles on a single tank of diesel fuel in my Volkswagen Passat TDI station wagon – but some of us are not so thrilled about the pollutants emitted by that fuel. Diesel fuel and heating oil emit high levels of sulfur oxides, hydrocarbons, particulates, and like all fossil fuels – carbon dioxide. We’d like to do better.
We can do better – with biodiesel.
What is Biodiesel?
Biodiesel is a diesel-like fuel derived from vegetable oil or other renewable sources. It can be made from soy or canola oil, even animal fats. Technically, it is a fatty acid methyl ester. Soy oil is the most common feedstock in the U.S. This feedstock is very chemically different from straight vegetable oil, which some people are also using as a substitute for diesel fuel. “Grease car” conversions involve modifying a diesel vehicle with a second, heated fuel tank. If heated, stratight vegetable oil or filtered used cooking oil can be used in diesel vehicles.
The chemistry involved in producing biodiesel is simple enough that hundreds of renewable energy advocates around the country are making their own using very simple, crude reacting vessels in their garages or basements. The book From the Fryer to the Fuel Tank, by Joshua Tickell, provides recipes and procedures for making biodiesel from used cooking oil, often avaiilable free from restaurants. Some of the more industrious backyard biodiesel producers are even making soap out of the glycerin that is precipitated out as a by-product.
Biodiesel derived from waste cooking oil is arguably the greenest liquid fuel available because the primary ingredient is a post-consumer waste product. Most biodiesel today, however, is “virgin” produced from soy or canola crops. Both recycled-cooking-oil biodiesel and virgin biodiesel are being produced to meet ASTM Biodiesel Standard D6751, approved in December 2001. This new standard, in the works since 1994, for the first time provides a consistent biodiesel standard, allowing manufacturers to design (and warrant) equipment with biodiesel use in mind.
It may take a while before engine manufacturers are comfortable with the use of biodiesel. Currently. Ford, Dodge and Volkswagen all void warranties if biodiesel is used. Volkswagen, however, sells a “biodiesel kit” that includes a few modifications suggested if biodiesel is used. Biodiesel has a somewhat lower energy density and more oxygen than petroleum diesel.
Most biodiesel today is mixed with petroleum diesel. The most common mixture is B20, a mix of 20% biodiesel and 80% petroleum diesel. B100 (100% biodiesel) is being used successfully by some but is not as widely recommended or used, due to concerns about cold-weather performance, equipment compatibility, and cost.
Benefits of Biodiesel
Biodiesel is cleaner than petroleum diesel, results in far lower greenhouse gas emissions, is biodegradable, and offers the potential to reduce our dependence on imported oil. Indeed, given such a significant collection of advantages, it is remarkable that this fuel has received so little attention over the years – by the environmental community, by energy policy experts, and by the green building community.
Along with the measurable reductions in all pollutant emissions, burning it also reduces the offensive odor associated with diesel. 100% biodiesel smells more like a cooking smell!
Another important question is the amount of energy it takes to produce and transport it. Ethanol, for example, has been criticized because it takes almost as much energy to produce as is contained in the end-product fuel. The most recent USDA data shows for every unit of fossil-fuel energy used in ethanol production, 1.34 units of ethanol are produced.
With virgin biodiesel made from soybeans, the energy balance is far better. A 1998 report sponsored by the US DOE and USDA found that for every unit of fossil-fuel energy consumed in biodiesel production, 3.2 units of biodiesel are produced. That a 220% net energy gain. Petroleum fuels have a negative energy balance ( a net energy loss) because it takes energy to extract, process and transport that fuel.
The energy balance of biodiesel will improve more with a state-of-the-art plant, such as a newly completed facility built by West Central Soy in Ralston, Iowa. According to production manager Myron Danzer, this plant uses a continuous (rather than batch) process and recovers for reuse both process water and methanol. The plant achieves a 7:1 energy balance within the plant (they don’t have lifecycle data).
Producing biodiesel from waste cooking oil most likely achieves the highest energy balance, because the raw material is a waste product, so the only energy input for the vegetable oil component is in getting it to the processing facility.
Biodiesel is fully biodegradable, so spills are much less of a problem than with petroleum diesel. A 1993 Austrian study found that 98% of biodiesel biodegrades in three weeks. In 2001, when a rail car carrying 28,000 gallons of B100 biodiesel derailed in Arizona, the initial reaction was panic, as the local officials prepared to deal with a toxic diesel spill. When they discovered it was biodiesel, cleanup was easy.
The simplicity of biodiesel production means that plants can be built quickly and inexpensively, offering potential to rapidly scale up production. The National Biodiesel Board says the current production could be tripled in a year.
Biodiesel as Transportation Fuel
Biodiesel can substitute for petroleum in any vehicle designed to operate on diesel fuel. In fact, when Dr. Rudolf Diesel first developed the diesel engine in 1895, he intended that it would be operated on vegetable oils in addition to distillate oil. At the 1900 World Exhibition in Paris, he demonstrated his new engine using peanut oil, and in 1912 he said, portentously, that “the use of vegetable oils for engine fuels may seem insignificant today. but such oils may become in the course of time as important as petroleum and the coal tar products of the present time.”
Biodiesel can be used in cars, light and heavy trucks, with few or no modifications. Studies show that a 20% blend can be burned in any diesel engine with no modifications at all. At a higher concentration, the more aggressive solvents in biodiesel may degrade certain rubber parts. Biodiesel experts recommend replacing certain hoses, for example with products that resist degradation.
Because biodiesel is a better solvent than petroleum, it is likely to dissolve crud that’s been accumulating in the fuel tank. As a result, the fuel filter will probably need to be changed shortly after making the switch.
The most significant limitation as a transportation fuel is its cold-weather performance. It can gel at temperatures below 32 degrees F and must be mixed with petroleum diesel, kerosene or special additives in cold weather. For this reason ( and due to cost), most users of biodiesel as a transportation fuel use a relatively modest B20 blend – this is what I’m using in my VW Passat.
According to Dr. Tyson at NREL, gelling problems were experienced with a B35 blend. “We’ve seen no problems with B20,” she says. Currently, more than 200 vehicle fleets nationwide operate on a biodiesel blend – most wi
th B20, some with lower percentages, B10 or B5.
In warmer climates and during the warmer months in colder climates, some users are having great success with B100. Rockland Materials, Inc., in Phoenix, Arizona has been operating its entire fleet of trucks, as well as other machinery, on B100 biodiesel for about two years. The company has about 120 on-road vehicles (mostly ready-mix concrete trucks) operating without any problems. Grant Goodman, owner, estimates his trucks have driven close to a million miles on biodiesel. They made no modifications – they just started using it. Using biodiesel may even extend engine life, due to its superior lubricating properties.
Using biodiesel instead of petroleum diesel costs the company roughly $200,000-300,000 more per year. When asked how he can justify that cost economically, he said he can’t. “It’s just the right thing to do,” he says. Goodman was quoted in Soybean Digest as saying,”It would nauseate me if I were running all these trucks and knew I could do something about our air quality and didn’t. In trucking, we have a huge opportunity to impact the environment positively if choose to do so.”
Off-Road Fuel for Heavy Equipment
The benefits are even greater for off-road equipment. Off-road diesel fuel does not have to meet federal low-sulfur standards (500 ppm) and sulfur levels of 2000-3000 ppm are typical. High sulfur petroleum is widely used on thousands of job sites in everything from bulldozers and excavators to cranes and compressors.
Rockland Materials has been operating loaders, excavators, rock-crushers, mining equipment, and generators on B100 without incident. And it hasn’t affected equipment warrantees either. “We have the blessings from Caterpillar and Cummins to do that,” Goodman says.
Biodiesel as Heating Fuel
Heating oil is a regional fuel used predominantly in the Northeast – 80% of residential heating oil and 49% of commercial is consumed in the six New England and Mid-Atlantic states. Most of this is high sulfur content distillate oil. These applications are prime candidates for biodiesel.
Because heating oil is used primarily in winter months, delivery and storage are significant concerns with biodiesel. The higher the biodiesel fraction, the higher the temperature at which gelling will occur. This characteristic is known as the “pour point” (the temperature below which the fuel will not pour). For standard petroleum, the pour point is -11F (-24C). For B20 it is 0F (-18C), and for B100 it is 32F (0C).
Biodiesel should be stored at a temperature well above its pour point. For B100, this means storage indoors in a heated space or in an underground tank, depending on the climate. Even B20 may need to be stored underground or indoors in the coldest climates.
The Warwick, Rhode Island School District has been testing various mixes of biodiesel as a heating fuel for the past two heating seasons. Bob Cerio, energy manager for the school system, calls it “the best thing since sliced bread.” Following a successful first season of biodiesel use, Cerio began using B20 in all the boilers and he’s had no problems at all. His testing shows a reduction in all pollutants, including NOx.
Using biodiesel has increased fuel costs for the Warwick School District. The biodiesel is delivered as B100 and mixed in their tanks. cost of the B100 ranges from $1.30-$1.76 per gallon. This season, he guesses the cost premium will be about 10 cents a gallon. The higher price hasn’t been an obstacle so far. “Our school district is willing to spend extra money to get a cleaner fuel that will expose our children to less pollution.” Cerio is also integrating energy conservation issues in the curriculum and notes that conservation efforts have saved $2 million in energy costs over the past four years – 25%. If the biodiesel is considered as part of the package, the overall savings are significant.
The Chewonki Foundation in Wiscasset, Maine has also been using biodiesel as heating fuel off and on for the past two years. They started out by purchasing commercially produced B100 but began making their own biodiesel from used cooking oil two years ago. Peter Arnold, of the nonprofit environmental educational organization, picks up the used cooking oil from area restaurants. He hoists 55-gallon drums into his truck using a small hydraulic barrle hoist mounted in the bed. Back at the Chewoonki Foundation, he processes the oil into biodiesel in an old pole barn now known as the Biodiesel Center. Currently, he’s producing 3000-5000 gallons of B100 per year.
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For More Information:
National Biodiesel Board
US EPA Office of Transportation & Air Quality
US DOE National BioFuels Program
World Energy
Chewonki Foundation
Excerpted FROM Environmental Building News, January 2003, a SustainableBusiness.com Content Partner
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